The purpose of this study is to examine whether giving large amounts of intravenous (IV) fluids will reduce the risk of developing a complication known as post-ERCP pancreatitis (PEP). Pancreatitis is inflammation of the pancreas, and it is the most frequent serious complication of ERCP. Typically, a small amount of IV fluids are given during this procedure (~ 1 liter). We are testing whether using a larger amount of fluids (2 - 3 liters) will reduce the risk of PEP.